A worker uses a lawn trimmer on an unusually cool July day at the Arkansas State Capitol in Little Rock, Ark., Monday, July 28, 2014. / Danny Johnston, AP

by Doyle Rice, USA TODAY

by Doyle Rice, USA TODAY

Summer heat was on holiday in much of the central U.S. last month: Most of the region had a very cool July, with 13 states seeing July temperatures that ranked among the 10 coldest since weather records began in 1895, NOAA's National Climatic Data Center reported Tuesday.

Both Indiana and Arkansas had their all-time coldest July on record. Indiana was a whopping 5.3 degrees below average in July, while Arkansas was 4.6 degrees below average.

While the central U.S. shivered in July, the heat continued to scorch the West. Six states sweltered through one of their 10 hottest Julys on record.

Meridional flow is the term used to describe the air flow pattern far above the Earth's surface, which has very large low-pressure troughs and high-pressure ridges embedded in it. Unlike zonal flow, meridional flow often brings extreme weather and strong temperature contrasts to the USA.

"Cooler-than-normal temperatures dominated the central and eastern U.S. beneath a strong upper-level long-wave trough, while warmer- and drier-than-normal weather prevailed across much of the West due to an intense upper-level ridge," the climate center reported.

Cities such as Indianapolis, Pine Bluff and Jonesboro, Ark., and Tupelo and Vicksburg, Miss., all had their coolest Julys on record, the Weather Channel reports.

Though parched California has seen its warmest January-July on record, nationally, the first seven months of the year have trended on the chilly side. The USA is seeing its coolest year since 1993.

Global climate data for July will be released next Monday, the NCDC reports. The ongoing chill in the U.S. so far this year has not been the case elsewhere on Earth. June was the third straight month that temperatures tied or broke record highs worldwide.

If July turns out to be record warm around the world, it would mark the warmest single month since records began.